A stepper (reduction projection exposing apparatus) as one of manufacturing apparatus of semiconductor devices is such an apparatus that a pattern formed on a photomask, a reticle, or the like is reduced and projected by a projecting lens onto a semiconductor wafer coated with a resist.
In recent years, in association with microminiaturization of a pattern formed, a method whereby the formed pattern is measured or inspected by a scanning electron microscope or the like and its appearance state is evaluated is becoming a main stream of the measurement and inspection of a semiconductor. The scanning electron microscope is such an apparatus that by scanning an electron beam onto a sample, electrons which are emitted from the sample are detected, thereby forming an image. That is, since two regions in which emission amounts of secondary electrons are almost equal are represented at an almost same luminance, there is a possibility that it is difficult to identify those regions. There is a case where when noises are mixed into the electron microscope image, it is also difficult to identify them. Particularly, in association with the recent realization of a high integration degree of pattern, the number of patterns which are difficult to be identified is increasing. Methods of identifying a line pattern and a space of a line-and-space pattern have been disclosed in Patent Literatures 1 and 2. Specifically speaking, Patent Literature 1 discloses the method of discriminating a convexity and a concavity in a line pattern constructed by the convexities formed by two vertical slopes and one kind of concavity. Patent Literature 2 discloses the method whereby on the basis of a comparison between peak widths of two adjacent profiles acquired by obliquely irradiating a beam to an ideal optical axis, whether a portion sandwiched by the two peaks is a line pattern or a space is discriminated.
Even if it is difficult to discriminate in the case of using only a two-dimensional image of a pattern, a kind of pattern can be specified by monitoring a three-dimensional structure including a depth direction of a sample. As a method of observing a three-dimensional structure of a pattern, Patent Literature 3 discloses the method whereby images acquired by observing a sample from two different directions are synthesized and the three-dimensional structure of the pattern is estimated. Patent Literature 4 discloses the method whereby a beam is irradiated to a pattern on a sample from an oblique direction and dimensions of an upper surface and a bottom surface of the pattern are individually measured.
In Non Patent Literatures 1, 2, and 3, in semiconductor processes, methods of forming a fine pattern by repeating an exposure and an etching two times have been described.